1. Field of the Invention
The present invention relates to a body-felt vibration unit wherein a sound signal from a sound device is converted into vibration through an electro-mechanical vibration transducer to vibrate a vibration transmitting member installed on a thing for the human body to be placed on (hereinafter referred to as "human body support member"), for example, a chair, a bed, etc., thereby giving the user a bodily sensation of vibration. The present invention also relates to a method of transmitting the vibration in the above-described body-felt sound unit.
2. Prior Art
The present inventors have been conducting studies, for a long time, of body-felt sound unit that converts a sound signal received from a sound device or the like into mechanical vibration and allows the user to receive this vibration by his/her body, together with sound from a speaker or a head receiver, and we have already obtained many patent rights and utility model rights (for example, see Japanese Patent Publication Nos. 58-2517, 57-9272, and 58-9640, and Japanese Utility Model Publication Nos. 64-6622, and 58-4316). All the sensible vibration units disclosed in these publications have a structure in which an electro-mechanical vibration transducer is imbedded in or attached to a human body support member, for example, a chair, and vibration that is generated from the electro-mechanical vibration transducer is applied to the user's body through a vibration transmitting member or the human body support member.
This type of body-felt vibration unit is designed to allow the user to feel low bass frequencies generated from an electric signal in the bass region by the vibration of the eardrum and the bodily-sensation of vibration with a view to relaxing the user mainly through the appreciation of music with an intensified feeling of being at a live performance, or through the bodily sensation of vibration by the vibration signal alone,, without music. Accordingly, body-felt vibration units, which have been proved to be effective medically or psychiatrically, are used in a wide field of application.
As to the electro-mechanical vibration transducer (hereinafter referred to as simply "transducer") that is employed in the above-described body-felt vibration unit, a basic type of transducer has already been disclosed in U.S. Pat. No. 4,750,208.
Transducers which are usable for the body-felt vibration unit include an electrodynamic type of transducer and an electromagnetic type of transducer, both of which are arranged such that a vibrating part thereof vibrates in accordance with the intensity of the input signal to cause a vibration transmitting member, which is imbedded in or attached to a human body support member, to vibrate in the direction of vibration of the vibrating part, so that the vibration is transmitted to the user's body in a direction normal to it. This vibration will hereinafter be referred to as "longitudinal vibration".
The above-mentioned Japanese Patent Publication No. 58-2517 deals with an invention relating to a cushioning member that is to be interposed between a vibration transmitting member and the human body, and gives a description of the feeling that the user has when sitting on the chair, for example, as a human body support member, and the uniform dispersion of the vibration that is applied to the user's body in a direction normal to it. Japanese Patent Publication No. 57-9272 also discloses a combination of a vibrating plate and a cushioning member, but this invention aims at efficiently transmitting vibration to the user's body. The inventions in the other three publications described above disclose a means for reducing the size and weight of the transducer and a method of attaching the transducer to a human body support member. All of these three inventions relate to a device to allow the user's body to receive efficiently a sound signal in the low-frequency region from a vibration transmitting member.
If a body-felt vibration unit is arranged such that vibration that is generated from a transducer is transmitted to the user's body through a human body support member, as described above, it is likely that all or part of the user's weight will be applied to the transducer, as a matter of course. It is therefore necessary to improve the human body support member or the transducer so that the transducer will not be damaged even if the user's weight is applied thereto. In other words, a reinforcing member or the like is needed in order to prevent application of unnecessary external force to the transducer, resulting in problems, such as an increase in the overall size of the apparatus.
Further, from the viewpoint of the structural association of the transducer with the vibrating plate, disclosed in the above-described publications, the vibration transmitting plate that vibrates sympathetically to the vibration generated from the transducer must have a plate-shaped configuration and the plate-shaped member must be vibrated in the direction of the thickness thereof in order to attain the purpose thereof. In this case, the arrangement is such that, no matter where the transducer is imbedded in the human body support member, the vibration from the vibrating plate is transmitted to the user's body in a direction normal to it. Accordingly, the user's weight forms longitudinal vibration that is counter to the direction of vibration of the vibration transmitting member.
In addition, since the transmission of vibration from the transducer to the vibration transmitting member is effected convergently, it is necessary in order to transmit uniform vibration to the whole vibration transmitting member to increase the thickness of the vibration transmitting member itself or to take into consideration the necessity of a structure in which transducers are dispersedly disposed.